Aliphatic or cycloaliphatic compounds containing at least six carbon atoms are treated in the liquid phase with a gaseous oxidant in the presence of a catalyst comprising (1) a salt of an alkali or alkaline-earth metal, magnesium, or aluminium with a higher carboxylic acid, i.e. a carboxylic acid containing at least six carbon atoms, and (2) a salt of a heavy base metal with a higher carboxylic acid. The materials which may be treated include montan wax, paraffin wax, ceresine, paraffin oil, heavy or middle oils, gas oil, naphthene hydrocarbons, hydrocarbons obtained from coal, brown coal, tar or mineral oils by destructive hydrogenation or low-temperature carbonization, animal or vegetable oils or fats such as wool fat, coconut, sesame, repeseed, cottonseed, linseed, or castor oils or residues from the purification of these materials, fractions of turpentine oil boiling above 300 DEG C., and non-aromatic alcohols and ketones obtainable from hydrocarbons by oxidation. The oxidant may be oxygen, air, or a mixture of oxygen or nitrogen oxides with air. The reaction temperature may be 100-200 DEG C., preferably 130-170 DEG C. The proportion of catalyst does not exceed about 3 per cent of the material treated. The reaction products generally include acids, esters, alcohols, aldehydes, and ketones. The carboxylates forming the catalyst may be oleates, naphthenates, palmitates, cinnamates, abietates, or other resinates, or salts of crude or isolated acid oxidation products of hydrocarbons. Catalysts specified as suitable are mixtures of such carboxylates of lithium and cerium; sodium and mercury; calcium and mercury; calcium and cerium; barium and mercury; sodium and vanadium; sodium and chromium; sodium and manganese; sodium and iron; magnesium and vanadium; magnesium and chromium; calcium and vanadium; calcium and chromium; calcium and manganese; barium and vanadium; barium and chromium; barium and iron; aluminium and vanadium; aluminium and manganese; potassium and manganese; potassium, aluminium, and manganese; sodium, aluminium, and vanadium; chromium, vanadium, and an alkali or alkaline-earth metal, magnesium, or aluminium. The catalyst may be added in one batch or in portions during the process. In the examples, (1) neutral oxidation products of paraffin wax are treated at 155 DEG C. with dry air in the presence of sodium palmitate and vanadium palmitate; (2) a turpentine fraction boiling above 500 DEG C. is treated with air at 165 DEG C. in the presence of aluminium palmitate, sodium palmitate, and vanadium palmitate; coconut oil or wool fat may be treated in the same way. Details are given also of a series of experiments in which a middle oil is oxidized in the presence of the following catalysts:--(1) nickel borate; (2) manganese borate; (3) manganese borate and calcium oxide; (4) manganese palmitate; (5) nickel palmitate; (6) copper palmitate; (7) sodium palmitate and manganese palmitate; (8) calcium palmitate and manganese palmitate; (9) sodium palmitate and nickel palmitate; (10) sodium palmitate and copper palmitate. Reference is made also to the use, as components of the catalysts, of higher carboxylates of rubidium, cesium, or strontium on the one hand, and zinc, cadmium, titanium, zirconium, thorium, tin, lead, antimony, bismuth, molybdenum, tungsten, uranium, cobalt, niobium, or thallium on the other hand. Specifications 12806/84, 122,696, 123,791, 137,878, 156,141, [all in Class 91, Oils &c.], 174,642, 252,327, 255,020, 256,922, 257,886, 303,268, 310,069, 324,903, [all in Class 2 (iii), Dyes &c.], and 333,690, [Class 91, Oils &c.], are referred to.ALSO:Aliphatic or cycloaliphatic compounds containing at least 6 carbon atoms are treated in the liquid phase with a gaseous oxidant in the presence of a catalyst comprising (1) a salt of an alkali or alkaline earth metal, magnesium, or aluminium with a higher carboxylic acid, i.e. a carboxylic acid containing at least 6 carbon atoms, and (2) a salt of a heavy base metal with a higher carboxylic acid. The carboxylates forming the catalyst may be oleates, naphthenates, palmitates, cinnamates, abietates or other resinates, or salts of crude or isolated acid oxidation products of hydrocarbons. Catalysts specified as suitable are mixtures of such carboxylates of lithium and cerium; sodium and mercury; calcium and mercury; calcium and cerium; barium and mercury; sodium and vanadium; sodium and chromium; sodium and manganese; sodium and iron; magnesium and vanadium; magnesium and chromium; calcium and vanadium; calcium and chromium; calcium and manganese; barium and vanadium; barium and chromium; barium and iron; aluminium and vanadium; aluminium and manganese; potassium and manganese; potassium, aluminium, and manganese; sodium, aluminium, and vanadium; chromium, vanadium, and an alkali or alkaline earth metal, magnesium, or aluminium. In the examples, catalysts used are (1) sodium palmitate and vanadium palmitate, and (2) aluminium palmitate, sodium palmitate, and vanadium p palmitate. Details are given also of a series of experiments in which a middle oil is oxidized in the presence of the following catalysts: (1) nickel borate; (2) manganese borate; (3) manganese borate and calcium oxide; (4) manganese palmitate; (5) nickel palmitate; (6) copper palmitate; (7) sodium palmitate and manganese palmitate; (8) calcium palmitate and manganese palmitate; (9) sodium palmitate and nickel palmitate; (1) sodium palmitate and copper palmitate. Reference is made also to the use, as components of the catalysts, of higher carboxylates of rubidium, caesium, or strontium on the one hand, and zinc, cadmium, titanium, zirconium, thorium, tin, lead, antimony, bismuth, molybdenum, tungsten, uranium, cobalt, niobium, or thallium on the other hand. Specifications 12806/84, 122,696, 123,791, 137,878, [all in Class 91, Oils &c.], 156,141, 174,642, 252,327, 255,020, 256,922, 257,886, 303,268, 310,069, 324,903, [all in Class 2 (iii), Dyes &c.], and 333,690, [Class 91, Oils &c.], are referred to.